1. Field of the Invention
This invention relates to a camera fit for a film unit having film, a cartridge containing the film therein and means on which particular information in recorded.
2. Related Background Art
Cameras of this type include those disclosed in U.S. Pat. Nos. 4,860,037 and 4,864,332. The cameras disclosed in these patents are both fit for a film unit in which a magnetic recording part is provided on the leader portion of film. In such cameras, when this film unit is loaded into the camera and photographing is performed and the midroll interrupt operation for taking the film unit out of the camera before all the frames of the film are photographed is applied, the rewinding of the film is started. During the rewinding, information regarding the number of photographed frames is recorded on the magnetic recording part through a magnetic head disposed in the film feeding path of the camera. When the film unit having such information recorded on the magnetic recording part is again loaded into the camera, the winding of the film is started. During the winding, the information of the number of photographed frames recorded on the magnetic recording part through the magnetic head is read out. This winding is controlled in conformity with the read-out information of the number of photographed frames, and is stopped when the unphotographed frame to be photographed next time is brought to a photographing position opposed to a photo-taking lens. Thereafter, photographing can be continued from that unphotographed frame. When the information that all frames have been photographed is read out from the information recording part, the film is rewound into the cartridge for the purpose of double exposure prevention, and the photographing operation is prohibited from being performed and a warning to that effect is given. The cameras described above are cameras of the so-called ordinary wind mode in which photographing starts from the frame which is most adjacent to the leader portion of the film.
U.S. Pat. No. 4,878,075 also discloses a camera which performs a similar function. However, the film unit fit for this camera has a magnetic recording part provided near each frame on film. In this camera, each time a frame is photographed, the information that the frame has been photographed is recorded on the magnetic recording part by a magnetic head. This camera is a camera of the so-called prewind-mode in which after all frames have once been wound, photographing is performed from the frame which is on the most distal end side (the magazine shaft side in the cartridge) and each time photographing is completed, rewinding is effected by one frame. Therefore, the film unit is once taken out of the camera and then is again loaded into the camera, the camera, the information on the magnetic recording part is read out by the magnetic head while the winding is performed, and the winding is stopped when the information to the effect that the frame is photographed frame is read out. And when rewinding of film is started and an unphotographed frame which is next to the photographed frame is advanced to a photographing position, the rewinding is stopped. Thereafter, photographing can be continued from the unphotographed frame. When all frames have been photographed, the film is rewound into the cartridge without the information of unphotographed frames being read out. The camera detects by a switch provided in a film feeding path that all the frames of the film have been photographed and therefore all the film has been rewound into the cartridge, that is, the film is absent in the film feeding path, and in this case, the camera gives a warning to that effect.
In any of the above-described cameras, the operation for reading out the information regarding photographed frames from the magnetic information recording part on the film is also performed when a new film unit that has never been loaded into the camera is loaded into the camera. Such information is not recorded on such new film and therefore, the reading-out operation in this case leads to the waste of electric power.